Adjustable tone volume control device for chime signals



1940- J. H. WHEELOCK EI'AL 2,223,144

ADJUSTABLE TONE VOLUME CONTROL DEVICE FOR CHIME SIGNALS Filed Nov. 24,1957 7755 77 fiMee/ac/f flan/1 a a W7 Patented Nov. 26, 1940 UNITEDSTATES PATENT OFFICE ADJUSTABLE TONE VOLUME CONTROL DEVICE FOR CHIMESIGNALS I Application November 24, 1937, Serial No. 176,308

5 Claims.

The present invention relates to audible signals of the type wherein aplunger is caused to strike a resonant metallic member, or chime bar.According to the present invention, there is provided improved means foradjustably controlling the volume of the sound given off when theresonant member is struck, so that only a pure tone will be heard,having the desired characteristics, as to loudness or softness.

The above and other advantageous features of the invention willhereinafter more fully appear from the following description, consideredin connection with the accompanying drawing, in which:

Fig. 1 is a view in front elevation of a chime signal provided with anadjustable tone control device embodying the invention.

Fig. 2 is a View, partially in side elevation and partially in section,of the device of Fig. 1.

Fig. 3 is a fragmentary sectional View along the line 3-3 of Fig. 1,illustrating the adjusting device on an enlarged scale.

Fig. 4 is a plan view of the parts of Fig. 3.

Referring to the drawing, the signal consists of a frame I partially ofmagnetic material, providing rods 2 for supporting a chime bar 3 abovethe top of the frame I. The bar 3 is supported by cords 4 extendingbetween the rods 2, with felt Washers 5 provided at the points ofsupport, so that the bar 3 is entirely out of metallic contact with therods 2 and frame I. A hollow resonator 6 is mounted on the rods 2 abovethe bar 3.

The frame I provides a recess la, in which is received a solenoid I, anda plunger 8 of magnetic material is movable Within an insulating tube 9,extending centrally through the solenoid I. With the solenoid I indeenergized condition, the plunger 8 rests at the bottom of the tube 9,with its upper end partially within the solenoid, so that when thesolenoid I is energized, the plunger 8 is drawn upwardly within thesolenoid with its upper end extending through an opening I0 in the frameI. A striker II is interposed between the chime bar 3 and the openingIll, and the striker II is mounted at the free end of a resilient memberI2, here shown in the form of a leaf spring, having its other endsecured to the top of the frame I at I3. The spring member I2 is offsetfrom the top of the frame I, so that the striker II is normallypositioned out of engagement with both the chime bar 3 and the top ofthe frame I.

The striker II carries washers I4 of non-metallic material, such asfelt, which are suitably secured, as by cement, to the metallic body ofthe striker II that is attached to the spring member I2. Consequentlywhen, in response to energization of the solenoid I, the plunger 8 movesthe striker II into engagement with the chime bar 3, there is nometal-to-metal contact between the parts, and the chime bar 3 gives offa clear fundamental note. As previously pointed out, the presentinvention contemplates means for controlling the tonal characteristicsof the sound given off by the chime bar, and a device for this purposeis shown in detail in Figs. 3 and 4.

A lever I5 is pivoted at I6 on a bracket IL with its free end bearing onthe spring member I2 between the striker II and the fixed endof themember I2. The lever I5 provides an upwardly extending arm I3 beyond itspivot I5, and a screw I9 threaded into an extension I'Ia of the bracketI1, bears on the lever arm I8. With the parts in the position of Figs. 1and 3, the setting of the adjusting screw I9 is such that the lever I5bears on the spring member l2 with sufiicient pressure to impart aninitial downward deflection thereto, which tends to bias the striker IIaway from the chime bar 3, and towards the plunger opening I0.Consequently, when the plunger 8 moves upwardly to hit the striker inresponse to energization of the solenoid I, the movement of the strikerII at the end of the spring member I2 is damped, due to the restrainingpressure of the lever I5. Therefore, when the striker II hits the chimebar 3, the volume and duration of the resulting sound have valuesdetermined by the setting of the adjusting screw I9.

When it is desired to decrease the volume, the screw I9 is turned so asto cause the free end of the lever I5 to move downwardly, and. therebyincrease the initial flexure of the spring member I2. Consequently, themember I2 offers more resistance to upward movement of the striker IIwhen hit by the plunger 8, and the chime bar 3 is struck a comparativelylight blow. Turning the screw I9 in the opposite direction to relievethe initial flexure of the spring member I2 reduces the damping effect,thereby increasing the force of the blow of the striker II on the chimebar 3 for a given upward force developed by the plunger 8, with aresulting increase of sound volume. Thus, by manipulating the screw I9,a soft, medium or loud tone can be obtained from the signal.Furthermore, the lever I5 always functions to prevent rebound of thestriker l l, which might otherwise occur were the spring I2 free tovibrate.

The strength of the blow imparted to the striker l I by the plunger 8,for a given excitation of the solenoid, is controllable by an adjustingscrew 20 at the bottom of the plunger tube 9. lhe lower end of theplunger 8 rests on the screw 20 when the solenoid l is deenergized, andthe setting of the screw 20 determines the degree to which the upper endof the lunger 8 extends within the solenoid I. By means of the screw 28,the length of the plunger stroke, and consequently the force of the blowstruck by the plunger 8, can be varied, to thereby obtain an additionalcontrol over the volume of sound given off by the chime bar 3 when hitby the striker I l.

The magnetic plunger 8 is surrounded by a thin sleeve 2| of non-magneticmetallic material, such as brass, the function of which is to providefor a certain amount of damping, due to the generation of eddy currentsin the sleeve. These eddy currents create a retarding effect on movementof the plunger in the solenoid, and make it necessary for the plunger tobecome thoroughly saturated, upon energisation of the solenoid, beforethe plunger 8 will move upwardly to hit the striker l l a single sharpblow, and such retardation of the plunger eliminates any tendencytowards premature movement thereof to impart a light blow to the strikerl 5. Furthermore, the non-magnetic sleeve 2| makes the plunger 8 lessliable to rattle in the tube 9 as it moves, due to the reduction ofsidewise pull on the plunger by the magnetic frame I. In other Words,the damping of the plunger 8 insures that the plunger will give only asingle quick stroke when the solenoid l is energized, and that therewill be no noise made by movement of the plunger in the tube, to detractfrom the quality of the tone of the chime bar when hit by the striker lI.

From the foregoing, it is apparent that by the present invention thereis provided a signal of the chime type, that isreadily controllable asto tonal characteristics and is free from any disturbing influences thatmight tend to adversely affect the quality of the fundamental notesounded when the signal is operated.

We claim:

1. A device of the class described, comprising a resonant member, aplunger movable toward said resonant member, a striker interposedbetween said resonant member and said plunger for cushioning thestriking force of the plunger, and means for adjusting the amount ofcushioning effect for controlling the tone volume of the fundamentalnote emitted by said resonant member, when hit by said striker.

2. A device of the class described, comprising a metallic resonantmember, a metallic plunger movable toward said resonant member, astriker providing a non-metallic portion interposed between saidresonant member and said plunger for cushioning the striking force ofthe plunger, and adjustable means cooperating with said striker to varythe volume of the sound given on" by said resonant member, when hit bysaid striker.

3. A device of the class described, comprising a metallic resonantmember, a metallic plunger movable toward said resonant member, aresiliently mounted striking member providing a nonmetallic cushioningportion between said resonant member and said plunger, and adjustablemeans for setting up a tension in said striking member to determine thetone volume of the sound given 011 by said resonant member, when hit bysaid striking member.

4. A device of the class described, comprising a metallic chime bar, ametallic plunger movable toward said chime bar, a resilient memberanchored at one end and carrying at its free end a non-metalliccushioning striker interposed between said bar and said plunger, andadjustable means for exerting a pressure on said resilient memberintermediate its ends to exert a damping effect on said striker.

5. A device of the class described, comprising a metallic chime bar, ametallic plunger movable toward said chime bar, a resilient memberanchored at one end and carrying at its free end a non-metalliccushioned striker interposed between said bar and said plunger, 2.pivotally mounted member having one end bearing on said resilientmember, and means for adjusting the degree of pressure exerted onsaidresilient memher by said pivoted member to control the volume andduration of sound given off by said chime bar when hit by said striker.

JOHN H. WI-lEELOCK. FRANK SCHERMA.

